Transit-exclusive lanes can speed buses or other transit vehicles and make the services more appealing and predictable. But those nearly-empty lanes can seem appealing to the drivers of private vehicles stuck in traffic or looking for short-term parking or loading, so keeping the lanes clear for transit can be a challenge. Cameras currently being used to enforce speed or red-light running, as well as cameras mounted on the buses themselves, might improve enforcement, as suggested by a recent Mobility Lab post.

Clearing dedicated bus lanes of unauthorized vehicles allows bus transit systems to operate more efficiently and successfully, possibly leading to reduced congestion for other road users. Once bus lanes are installed and signed appropriately, and road users are educated as to their existence and exclusivity, enforcement plays a primary role in keeping them clear and working as planned.

Police enforcement, where an officer tickets those who enter, stand, or park in bus lanes, can cause further congestion by detaining the offender in the bus lane and forcing buses into traffic. A significant police presence may be required to maintain the perception that violations are enforced, and to issue citations. Such presence can require robust financial investment in personnel.

Automated enforcement would be both a cheaper and more consistent way to keep the lanes clear. It has been adopted by some transit agencies, but is impeded by state law in much of the U.S. Even red-light and speeding cameras are not present in all states, as this on-line map demonstrates.

Cameras for automated enforcement can be stationary, or they can be mobile when affixed to buses. Both versions have pros and cons. Detection can be incomplete if an insufficient number of stationary cameras are deployed. Bus-mounted camera enforcement has the advantage of patrolling the entire bus network at regular intervals, but the disadvantage of not monitoring the lanes continuously.

Seoul, South Korea, has used bus-mounted automated enforcement since 2004, and has seen a turn-around in bus ridership. In the U.S., by state law, only New York and California allow automated enforcement of bus lanes. New York City MTA’s Select Bus Service uses bus-mounted cameras to record stationary violations, while the NYCDOT uses stationary cameras to record moving violations in bus-only lanes. San Francisco’s SFMTA MUNI buses use forward-mounted cameras to enforce transit-only lanes. Baltimore, Philadelphia, and Seattle are each currently exploring the possibility of following suit.

Automated enforcement—where violations are detected using cameras—generally requires legislative accommodation. There is often public resistance to automatic enforcement, but that can change as the benefits become clear. The number of citations issued would be expected to decrease over time as public awareness spreads. For bus-mounted cameras, transit and enforcement agencies would need to work together to allow footage from bus-mounted surveillance cameras to be used for enforcement.